This disclosure generally relates to a system for controlling turbomachine fuel flow. Turbomachines, such as gas turbine engines, typically include at least a compression section, a combustor section, and a turbine section. Many engines include a fuel control system configured to deliver fuel to the combustor section. These systems may include a windmill bypass valve that directs fuel away from a fuel delivery valve, such as a minimum pressure shutoff valve (MPSOV), during engine shutdown. Further, the windmill bypass valve may maintain sufficient pressure (sometimes called “muscle” pressure) to position fuel control system components as well as various engine actuators during windmilling and start. Shutdown of the engine may occur on the ground or in flight during, for example, an over-speed condition.
One example fuel control system includes a windmill bypass valve selectively movable between an open position and a closed position. When in the open position, some fuel is directed away from an MPSOV, and thus the pressure of the fuel flowing to the MPSOV drops. This drop in pressure allows the MPSOV to close under the bias of a spring and shut off a flow of fuel to the engine.